Windows and particularly vehicle windows are frequently provided with self defogging and deicing capabilities by the surface application of electrical resistance elements. These electrical resistance elements are typically applied to the interior surface of the rear window of an vehicle such as an automobile, van, truck or the like and are sometimes referred to as backlight heaters. There are also applications for this technology in the marine and aircraft fields
While this approach of defogging and deicing vehicle windows has been quite satisfactory, there continues to be a need to reduce the response time of the type of electrical resistance elements particularly in the zones of the window which are vision critical.
Another pressing need in this general area is to accommodate larger rear windows in terms of providing the necessary defogging and deicing capabilities with the efficient use of materials involved in the application of the electrical resistance elements and their bus bars, all of which include a high silver content. In addition, in light of a vehicle's limited ability to provide additional power to such an application, it is important not to waste any of the available power.
A considerable amount of material is typically used in providing the power supply electrical connection points as may be specified by the vehicle manufacturer. High volume manufacturing techniques employed in the assembly of automobiles, vans and the like, dictate that both of the electrical connection points of the electrical resistance element defogging and deicing system be close together for efficient connection to the vehicle power supply system. Typically, the prior art electrical resistance element defogging and deicing systems require the use of extended length bus bars, braided elements and the like to accomplish the necessary proximity of the electrical connection points. These extended length elements not only require the excessive use of high silver content materials but also introduce an unwanted high voltage drop element into the heating system. The use of braided elements, to reduce the unwanted high voltage drop, also involves the additional expensive step of soldering to connect it to the heating system.
Windows of this type are one of many new electrical and electronic components and systems being used in vehicles which makes it all the more important that each such component and system, including electrical resistance element defogging and deicing systems, optimize the power consumption for its given task.